Install copyright_report files

Documentation files are excluded from installations made to the Docker images, with a few exceptions to this rule, including copyright files. This extends it to also include copyright_report files, as they are useful to have installed for the purpose of being able to examine dependencies' reports while building packages.

As the files are all plain text and shorter than the corresponding copyright file (as they omit the full license text), the effect on the built image sizes should be negligible.

https://phabricator.apertis.org/T8554

Signed-off-by: Ryan Gonzalez ryan.gonzalez@collabora.com